[问答题]
The image shows a fo c fks:fh 07,j7fjhir3od web6c .:vkfo;/qr(cgr4m ag7cw y in a salt marsh ecosystem.
1.Identify all the detritivores in the food web shown above.
2.Define secondary productivity.
3.Explain why energy is lost during the transfer from producers to herbivores.
4.Describe a method a farmer could use to estimate the gross primary productivity per month of his wheat crop.